Editing Merge (software)

{{Short description|Virtualisation software}}
{{for|other types of merge performed by software|Merge (disambiguation)#Computer science{{!}}Merge § Computer science}}
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{{Infobox software
| name = Merge
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| developer = [[Locus Computing Corporation]]
| released = {{Start date and age|1985|10|09|df=yes}}
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| operating system = [[OpenServer|SCO UNIX]]
| platform = [[Intel 8086]]
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'''Merge''' is a [[software]] system which allows a user to run [[DOS]]/[[Windows 3.1x|Windows 3.1]] on [[SCO UNIX]], in an [[Intel 8086|8086]] [[virtual machine]].

==History==
Merge was originally developed to run [[DOS]] under [[UNIX System V]] Release 2 on an [[AT&T 6300 Plus]] personal computer. Development of the virtual machine began in late 1984, and AT&T announced the availability of the machine on 9 October 1985,<ref name="Petrosky_1985"/> referring to the bundled Merge software as Simultask.<ref name="Welch_1986"/> (The PC 6300 Plus shipped with [[MS-DOS]] in 1985 though, because its Unix System V distribution was not ready until the end of March 1986.)<ref name="WithoutUnix_1986"/> Merge was developed by engineers at [[Locus Computing Corporation]], with collaboration from AT&T hardware and software engineers, particularly on aspects of the system that were specific to the 6300 Plus (in contrast to a standard [[IBM Personal Computer AT|IBM PC/AT]]).

The AT&T 6300 Plus contained an [[Intel 80286]] processor, which did not include the support for [[Intel 8086|8086]] virtual machines ([[virtual 8086 mode]]) found in the [[i386|80386]] and later processors in the x86 family. On the 80286, the DOS program had to run in [[real mode]]. The 6300 Plus was designed with special hardware on the bus that would suppress and capture bus cycles from the DOS program if they were directed toward addresses not assigned for direct access by the DOS virtual machine.<ref name="Prestinario_1986"/> Various system registers, such as the [[programmable interrupt controller]] (PIC), and the video controller, had to be emulated in software for the DOS process, and a [[watchdog timer]] was implemented to recover from DOS programs that would clear the interrupt flag and then hang for too long. The hardware used the [[non-maskable interrupt]] (NMI) to take control back to the emulation code.<ref name="Patent_4747040"/>

Later, Merge was enhanced to make use of the [[virtual 8086 mode]] provided by the 80386 processor; that version was offered with [[Microport Systems|Microport]] SVR3 starting in 1987,{{citation needed|date=February 2014}} and subsequently with [[SCO Group|SCO Unix]]. There was also a Merge/286 version that ran on an unmodified PC/AT (without any special I/O trapping hardware); it ran as long as the PC program was reasonably well-behaved, though a malicious or crashing program could take the unprotected UNIX kernel down on those machines. Even so, the notoriously ill-behaved ''[[Microsoft Flight Simulator]]'' would run on the PC/AT simultaneously with Unix.{{citation needed|date=February 2014}} These later versions were marketed directly by Locus as well as through some OEM and ISV channels. A product-evaluation version with user manual appeared in January 1987, with retail Version 1.0 of Merge/386 shipping in October of that year.

In the late 1980s, the main commercial competitor of Merge was [[VP/IX]] developed by [[Interactive Systems Corporation]] and [[Phoenix Technologies]].<ref name="Enterprise_1987"/> AT&T's Simultask 2.0 was based on VP/IX.<ref name="Inc_1989"/><ref name="Rosen_1990"/>

In 1992, [[Univel]] [[UnixWare 1.0 Personal Edition]] came with ''DOS Merge 3.0'' and [[Novell]]'s [[DR&nbsp;DOS 6.0]].

Locus eventually joined the [[Microsoft]] [[Windows Interface Source Environment|WISE]]<ref name="WISE_1995"/> program which gave them access to [[Microsoft Windows]] source code, which allowed later versions of Merge to run Windows ''shrink wrapped'' applications without a copy of Windows.<ref name="Locus_1995"/>

On 12 April 1995, [[Platinum Technology]] announced an agreement in principle to acquire Locus Computing Corporation for approximately {{currency|amount=33|code=USD}}&nbsp;million, about 1/4 of which was attributed to the Merge technology and product.{{citation needed|date=February 2014}} The acquisition went through, and Platinum went on to develop the SCO Merge 4 version with [[Windows 95]] support, which was released in 1998.<ref name="Magee_1998"/>

The Merge technology was bought by a company called DASCOM in 1999, which was in turn bought by [[IBM]]. A company called TreLOS was spun off in 2000 that continued the development of the virtual machine software and created [[Win4Lin]]. TreLOS later merged into NeTraverse, Inc.

The [[SCO Group]] distributes NeTraverse Merge 5.3, which supports their current products [[SCO OpenServer]] 5.x and [[UnixWare]] 7.<ref>{{Cite web |title=Xinuos, Inc. {{!}} Products {{!}} Merge {{!}} Merge_5 |url=http://www.sco.com/products/merge/Merge_5.3_US-7.html |access-date=2022-04-04 |website=www.sco.com}}</ref>

==Reception==
While criticizing the AT&T 6300 Plus as poor value, ''[[InfoWorld]]'' in 1986 praised Simultask's performance and DOS compatibility on the computer. Reporting that at least one [[terminal emulator]] ran on it but not on native MS-DOS on the 6300 Plus, the magazine estimated that Simultask's performance running DOS software was comparable to that of the original [[IBM PC AT]]. Also approving of the documentation and ease of installation, ''InfoWorld'' concluded that Simultask was "an elegant and reasonably priced one-box solution for those who want to access both Unix and MS-DOS".<ref name="satchell19860929">{{Cite magazine |last=Satchell |first=Stephen |date=1986-09-29 |title=With Simultask, 6300 Plus is Transformed |url=https://books.google.com/books?id=pzwEAAAAMBAJ&pg=PA54 |access-date=2024-08-17 |magazine=InfoWorld |publisher=InfoWorld Media Group, Inc. |pages=54–55 |language=en}}</ref>

==See also==
* [[Popek and Goldberg virtualization requirements]] ([[Gerald J. Popek|Dr. Popek]] was one of the founders of [[Locus Computing Corporation|Locus]])
* [[Windows Interface Source Environment]] (WISE)

==References==
{{reflist|refs=
<ref name="Petrosky_1985">{{cite news |author-first=Mary |author-last=Petrosky |title=6300 Plus Launched By AT&T |date=1985-10-14 |newspaper=[[InfoWorld]] |volume=7 |issue=41 |publisher=[[Popular Computing, Inc.]]<!-- a subsidiary of CW Communications, Inc. --> |issn=0199-6649 |pages=1, 8 |url=https://books.google.com/books?id=ii8EAAAAMBAJ&pg=PA1 |access-date=2020-02-10 |url-status=live |archive-url=https://web.archive.org/web/20200210164729/https://books.google.de/books?id=ii8EAAAAMBAJ&pg=PA1&redir_esc=y |archive-date=2020-02-10}}</ref>
<ref name="Welch_1986">{{cite news |author-first=Mark J. |author-last=Welch |title=Another Unix Project to Run DOS on 80386 |date=1986-06-30 |newspaper=[[InfoWorld]] |volume=8 |issue=26 |publisher=[[Popular Computing, Inc.]] |issn=0199-6649 |page=3 |url=https://books.google.com/books?id=Wi8EAAAAMBAJ&pg=PA3 |access-date=2020-02-10 |url-status=live |archive-url=https://web.archive.org/web/20200210165236/https://books.google.de/books?id=Wi8EAAAAMBAJ&pg=PA3&lpg=PA3&focus=viewport&hl=de |archive-date=2020-02-10 |quote=[…] [[Locus Computing Corp.|Locus]] previously developed Merge 286, now used by [[AT&T]]'s Simultask program to run one [[MS-DOS]] program under Unix on the [[80286]]-based [[6300 Plus]], according to Judi Uttal, director of marketing for Locus. […]}}</ref>
<ref name="WithoutUnix_1986">{{cite news |title=Even without Unix, Byers Like AT&T's PC 6300 |date=1986-01-13 |newspaper=[[InfoWorld]] |series=News |volume=8 |issue=2 |publisher=[[Popular Computing, Inc.]] |issn=0199-6649 |location=Morristown, NJ, USA |page=13 |url=https://books.google.com/books?id=mi8EAAAAMBAJ&pg=PA13 |access-date=2020-02-09 |url-status=live |archive-url=https://web.archive.org/web/20200210165635/https://books.google.de/books?id=mi8EAAAAMBAJ&pg=PA13&redir_esc=y |archive-date=2020-02-10}}</ref>
<ref name="Prestinario_1986">{{cite news |author-first=Jerry A. |author-last=Prestinario |title=Simultask Response |series=Review Responses |date=1986-12-15 |issn=0199-6649 |newspaper=[[InfoWorld]] |volume=8 |issue=50 |publisher=[[Popular Computing, Inc.]] |pages=71 |url=https://books.google.com/books?id=bDwEAAAAMBAJ&pg=PA71 |access-date=2020-02-10 |url-status=live |archive-url=https://web.archive.org/web/20200210170019/https://books.google.de/books?id=bDwEAAAAMBAJ&pg=PA71&redir_esc=y |archive-date=2020-02-10 |quote=[…] A recent Review Response stated that no special hardware is required to run Simultask [and therefore it could run on any 80286 computer]. Every [[PC 6300 Plus]] comes standard with special circuitry on the motherboard. This hardware is activated with Simultask to prevent programs from interfering with one another when they are running simultaneously. This is necessary because many [[MS-DOS]] programs have complete control of the hardware. Simultask uses this circuitry to ensure that, no matter what one program does, other programs that are running simultaneously will not be affected. Other computers can't provide this assurance. […]}}</ref>
<ref name="Enterprise_1987">{{cite news |title= Computerworld|newspaper=[[Computerworld]] |date=1987-10-26 |issn=0010-4841 |publisher=IDG Enterprise |pages=81– |url=https://books.google.com/books?id=3UuWcPxTGDIC&pg=PT81 |access-date=2020-02-09 }}</ref>
<ref name="Inc_1989">{{cite magazine |magazine=[[PC Magazine]] |date=1989-04-11 |publisher=[[Ziff Davis, Inc.]] |issn=0888-8507 |pages=[https://archive.org/details/bub_gb_jGnF7KJsyBQC/page/n153 152]– |url=https://archive.org/details/bub_gb_jGnF7KJsyBQC |access-date=2020-02-09 |title=PC Mag }}</ref>
<ref name="Rosen_1990">{{cite book |author-first1=Kenneth H. |author-last=Rosen |author-first2=Richard R. |author-last2=Rosinski |author-first3=James M. |author-last3=Farber |title=UNIX System V release 4: an introduction for new and experienced users |date=1990 |publisher=[[Osborne McGraw-Hill]] |location=Berkeley, USA |isbn=978-0-07-881552-2 |page=[https://archive.org/details/unixsystemvrelea00rose/page/934 934] |url=https://archive.org/details/unixsystemvrelea00rose/page/934 |url-access=registration}}</ref>
<ref name="WISE_1995">{{cite web |title=Windows Interface Source Environment (WISE) |date=January 1995 |url=http://hyper.sunjapan.com.cn/~hz/win32/wise.htm |access-date=2009-11-26 |url-status=dead |archive-url=https://web.archive.org/web/20080330032918/http://hyper.sunjapan.com.cn/~hz/win32/wise.htm |archive-date=2008-03-30}}</ref>
<ref name="Locus_1995">{{cite web |title=Locus announces availability of Merge 3.2 for SCO OpenServer Release 5 |date=1995-05-09 |url=http://www.thefreelibrary.com/Locus+announces+availability+of+Merge+3.2+for+SCO+OpenServer+Release+5-a016933936 |access-date=2009-11-26 |url-status=dead |archive-url=https://web.archive.org/web/20101204092756/http://www.thefreelibrary.com/Locus+announces+availability+of+Merge+3.2+for+SCO+OpenServer+Release+5-a016933936 |archive-date=2010-12-04}}</ref>
<ref name="Magee_1998">{{cite web |author-first=Mike |author-last=Magee |date=1998-02-19 |title=SCO runs Windows 95 apps on Unix |url=http://www.v3.co.uk/v3-uk/news/1977985/sco-runs-windows-apps-unix |url-status=dead |archive-url=https://web.archive.org/web/20140222002826/http://www.v3.co.uk/v3-uk/news/1977985/sco-runs-windows-apps-unix |archive-date=2014-02-22}}</ref>
<ref name="Patent_4747040">{{cite web |title=U.S. Patent: Dual Operating System Computer |url=http://patft.uspto.gov/netacgi/nph-Parser?patentnumber=4747040 |access-date=2020-02-10 |url-status=live |archive-url=https://web.archive.org/web/20200210170712/http://patft.uspto.gov/netacgi/nph-Parser?Sect1=PTO1&Sect2=HITOFF&d=PALL&p=1&u=%252Fnetahtml%252FPTO%252Fsrchnum.htm&r=1&f=G&l=50&s1=4747040.PN.&OS=PN%2F4747040&RS=PN%2F4747040 |archive-date=2020-02-10}}</ref>
}}

==External links==
* {{cite web |url=http://www.sco.com/products/merge/ |title=MergePro for SCO OpenServer and UnixWare}}
* {{cite news |title=Can CA save Linux from the great Satan SCO? |author-first=Maureen |author-last=O'Gara |date=2003-12-20 |newspaper=[[Computerworld New Zealand]] |issn=0113-1494 |id=CMPWNZ |volume=<!-- different from US issue --> |number=<!-- different from US issue --> |publisher=[[IDG Communications]] |url=http://www.computerworld.co.nz/article/504245/can_ca_save_linux_from_great_satan_sco_/ |url-status=dead |archive-url=https://web.archive.org/web/20160303223841/http://www.computerworld.co.nz/article/504245/can_ca_save_linux_from_great_satan_sco_/ |archive-date=2016-03-03}}

{{Unix–Windows interoperability}}

[[Category:Virtualization software]]